with the renewed interest in headers everyone seems to be over-looking the options...
06-08-2006, 05:53 AM
#11
AudiWorld Super User
Thread Starter
Intake side needs "rougher" walls for better flow as well as fuel atomization...
with smooth walls on the intake side fuel stays in large droplets/puddles and doesnt atomize very well before going into the combustion chamber. On the exhaust side a smoother surface allows less carbon buildup inside the runner walls tho "some" is inevitable. That smaller amount of carbon buildup provides a good amount of boundary layer roughness. If finish is too rough even more carbon and larger carbon crystals will cling tenaciously to the walls that will increase turbulence and restrict flow.
06-08-2006, 06:04 AM
#12
AudiWorld Super User
Thread Starter
Again, just because Extrude Hone is out of reach doesnt mean an incredibly good IM port/polish...
<center><img src="http://pictureposter.audiworld.com/711/intake37.jpg"></center><p>
cant be done. Several years ago we did a workshop here at this forum on the project. We covered "every" aspect from disassembly and clean-up of the IM to tools and sanding media to use. I know MrD still keeps a link to it thats in all of his posts.
My personal intake manifold was a Colossus project that included gasket-matching and porting/polishing every primary and secondary intake runner along its full-length. Not just at its entry/exit. When finished EVERY primary/secondary runner was CC'd to within one drop liquid volume until all primary and secondary runners had "EXACTLY" the same volume as each other (respectively) or at least within one drop of water. This along with equal-length headers is the "only" way to make equal HP/TQ in EVERY cylinder!
This pic shows an "over-polished" upper IM half with its secondary runners finished. The next step here was to go back inside with a 170 grit bead-blast media and blast the desired grit finish in after porting/polishing.
cant be done. Several years ago we did a workshop here at this forum on the project. We covered "every" aspect from disassembly and clean-up of the IM to tools and sanding media to use. I know MrD still keeps a link to it thats in all of his posts.
My personal intake manifold was a Colossus project that included gasket-matching and porting/polishing every primary and secondary intake runner along its full-length. Not just at its entry/exit. When finished EVERY primary/secondary runner was CC'd to within one drop liquid volume until all primary and secondary runners had "EXACTLY" the same volume as each other (respectively) or at least within one drop of water. This along with equal-length headers is the "only" way to make equal HP/TQ in EVERY cylinder!
This pic shows an "over-polished" upper IM half with its secondary runners finished. The next step here was to go back inside with a 170 grit bead-blast media and blast the desired grit finish in after porting/polishing.
06-08-2006, 06:16 AM
#13
AudiWorld Super User
Thread Starter
Pic 2; Lower IM half porting/polishing with bead-blasted runners for ideal grit finish...
<center><img src="http://pictureposter.audiworld.com/711/intake35.jpg"></center><p>with 3 coats of Glyptal to smooth out the floor. This lower half is also filled with aluminum epoxy in many places to eliminate depp pockets, recesses and voids that can trap air or cause turbulence. Also prevents it getting heavily soiled as nothing sticks to this stuff.
06-08-2006, 07:10 AM
#18
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hey mance, i thought the good surface roughness was from 80 grit paper...
am I getting that wrong? Or was that the MAF... i can't remember. I was gun ho to do this and now i just have a really clean IM sitting in my attic awaiting me to buy the tools to P&P :-P
06-08-2006, 07:23 AM
#19
AudiWorld Super User
Thread Starter
You're correct. I typo'd a "1" in as I use a 120 grit final flapper wheel then bead-blasted...
back to 70 grit and not "170." Doing it that way removes annular scoring left by the coarser grit flapper wheels. And I cannot buy 80 grit beads so I have to use either 70 or 110.
But a bead-blasted 70 grit without annular scoring is closer to an 80 grit finish done with a die grinder.
But a bead-blasted 70 grit without annular scoring is closer to an 80 grit finish done with a die grinder.
